Wireless Mobility Access for Unconfigured Target Cells
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Solution Overview
Problem
Existing mobility management in wireless communication systems, particularly in Integrated Access and Backhaul (IAB) networks, faces challenges in efficiently handling handover failures and optimizing mobility and random access processes, especially when a user equipment (UE) needs to connect to a target cell that is not pre-configured.
Innovation Solution
The method involves a user equipment (UE) receiving an RRC message with access configurations for target cells and dynamic access information, allowing it to perform mobility to a target cell based on random access preambles or cell information, even if the target cell is not pre-configured, thereby enhancing mobility management in IAB networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the UE is configured with pre-configured target cells for mobility, then the mobility management is simplified and faster, but the system cannot handle target cells that are not pre-configured (such as in IAB network failures)
Solution Approach 1:
The network node performs preliminary action by providing the UE with a list of candidate target cells and their access configurations in advance through RRC signaling. This allows the UE to have pre-prepared mobility information without needing actual handover to occur, enabling fast mobility when conditions permit while also having fallback options when pre-configured cells are unavailable.
Solution Approach 2:
The patent introduces an intermediary mechanism where the network node dynamically indicates which candidate cell the UE should access through lower layer signaling (MAC CE or DCI). This intermediary indication layer allows the system to flexibly select from pre-configured candidates or fall back to other mechanisms without requiring complete reconfiguration, thus bridging the gap between simplicity and adaptability.
2Adaptability or versatility
If the network provides detailed access configurations for multiple target cells, then the UE has more mobility options and can select optimal targets, but the signaling overhead and system complexity increase
Solution Approach 1:
The patent segments the mobility management into distinct phases: (1) RRC layer configuration where the network provides a list of candidate cells with basic access parameters, and (2) MAC/PHY layer dynamic indication where the network selects the actual target cell. This segmentation allows detailed configuration of multiple options without overloading the signaling during execution, as the heavy lifting is done in the configuration phase rather than the execution phase.
Solution Approach 2:
The network provides more candidate cells than it expects the UE to actually use (excessive action), but only the necessary selection information is transmitted dynamically. This allows the UE to have multiple mobility options available without requiring all of them to be actively managed simultaneously, reducing the operational complexity while maintaining versatility.
3Adaptability or versatility
If the UE performs random access to target cells without pre-configured access parameters, then the UE can access any available cell, but the random access time and reliability decrease
Solution Approach 1:
The network performs preliminary action by pre-configuring access parameters (such as RACH resources, physical cell identifiers, and access configurations) for multiple candidate target cells. When mobility is needed, the UE can immediately use these pre-configured parameters to perform random access without needing to discover or negotiate access parameters in real-time, significantly reducing access time while maintaining the ability to access any available cell.
Data Source
AI summary
The present disclosure relates to a mobility management in wireless communications. According to an embodiment of the present disclosure, a method performed by a user equipment (UE) in a wireless communication system comprises: receiving, from a network node, a radio resource control (RRC) message comprising access configurations for one or more target cells; receiving, from the network node, an indication, wherein the indication comprises access information; and performing an access to a target cell based on an access configuration for the target cell in the RRC message and the access information in the indication, wherein the access information comprises at least one of a random access preamble for the access or a target cell information for the access, and wherein the target cell information i) informs a cell identifier (ID) of a target cell not included in the one or more target cells configured for the UE, or ii) does not inform any cell ID.